The breached levee system at the 17th Street Canal has been independently studied by conducting total and effective stress analyses. Performance of the levee system during the hurricane duration was investigated with special attention focused on the formation of a gap between the levee fills and the floodwall, and on the localized shear strain in the lacustrine clay layer. In contrast to the total stress analyses conducted by the Interagency Performance Evaluation Task Force (IPET) and the Independent Levee Investigation Team (ILIT), the effective stress analysis presented in this paper considered the soil – pore water interaction, and demonstrated evidences of initiation and mobilization of the localized shear strain.